cv_utils.cpp

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// -*- mode: c++ -*-
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#include "jsk_recognition_utils/cv_utils.h"

namespace jsk_recognition_utils
{
  cv::MatND computeHistogram(const cv::Mat& input_image, int bin_size,
                             float min_value, float max_value,
                             const cv::Mat& mask_image)
  {
    int channels[] = {0};
    cv::MatND hist;
    int hist_size[] = {bin_size};
    float range[] = {min_value, max_value};
    const float* ranges[] = {range};
    cv::calcHist(&input_image, 1, channels, mask_image, 
                 hist, 1, hist_size,
                 ranges, true, false);
    return hist;
  }
  
  std::vector<jsk_recognition_msgs::HistogramWithRangeBin>
  cvMatNDToHistogramWithRangeBinArray(const cv::MatND& cv_hist, float min_value, float max_value)
  {
    std::vector<jsk_recognition_msgs::HistogramWithRangeBin> bins(cv_hist.total());
    const float bin_width = (max_value - min_value) / cv_hist.total();
    for (size_t i = 0; i < cv_hist.total(); i++) {
      const float left = i * bin_width + min_value;
      const float right = (i + 1) * bin_width + min_value;
      jsk_recognition_msgs::HistogramWithRangeBin bin;
      bin.min_value = left;
      bin.max_value = right;
      bin.count = cv_hist.at<float>(0, i);
      bins[i] = bin;
    }
    return bins;
  }

  bool compareHistogramWithRangeBin(const jsk_recognition_msgs::HistogramWithRangeBin& left,
                                    const jsk_recognition_msgs::HistogramWithRangeBin& right)
  {
    return left.count > right.count;
  }

  void sortHistogramWithRangeBinArray(std::vector<jsk_recognition_msgs::HistogramWithRangeBin>& bins)
  {
    std::sort(bins.begin(), bins.end(), compareHistogramWithRangeBin);
  }

  std::vector<jsk_recognition_msgs::HistogramWithRangeBin>
  topNHistogramWithRangeBins(const std::vector<jsk_recognition_msgs::HistogramWithRangeBin>& bins,
                             double top_n_rate)
  {
    int sum = 0;
    for (size_t i = 0; i < bins.size(); i++) {
      sum += bins[i].count;
    }
    const int target_sum = sum * top_n_rate;
    std::vector<jsk_recognition_msgs::HistogramWithRangeBin> top_n_bins;
    top_n_bins.reserve(bins.size());
    
    int current_sum = 0;
    for (size_t i = 0; i < bins.size(); i++) {
      jsk_recognition_msgs::HistogramWithRangeBin bin = bins[i];
      if (current_sum >= target_sum) {
        return top_n_bins;
      }
      top_n_bins.push_back(bin);
      current_sum += bins[i].count;
    }
    return top_n_bins;
  }

  void
  drawHistogramWithRangeBin(cv::Mat& image,
                            const jsk_recognition_msgs::HistogramWithRangeBin& bin,
                            float min_width_value,
                            float max_width_value,
                            float max_height_value,
                            cv::Scalar color)
  {
    if (max_height_value == 0.0) {
      return;
    }
    const int height = image.rows;
    const int width = image.cols;
    const int left = (bin.min_value - min_width_value) / (max_width_value - min_width_value) * width;
    const int right = (bin.max_value - min_width_value) / (max_width_value - min_width_value) * width;
    const int top = bin.count / max_height_value * height;
    if (bin.count == 0 || top == 0 || left == right || left < 0 || right >= width || top > height) {
      return;
    }
    
    cv::rectangle(image, cv::Point(left, height), cv::Point(right, height - top),
                  color, CV_FILLED);
  }
}